* Type annotations for `breadth_first_search.py`
* Type annotations for `breadth_first_search_2.py`
* Remove from excluded in mypy.ini
* Add doctest.testmod()
* Type annotations for `graphs/check_cycle.py`
* Type annotations for `graphs/greedy_min_vertex_cover.py`
* Remove from excluded in mypy.ini
* add check_cycle.py
* Update graphs/check_cycle.py
Co-authored-by: John Law <johnlaw.po@gmail.com>
* Update check_cycle.py
* Apply suggestions from code review
Co-authored-by: John Law <johnlaw.po@gmail.com>
Co-authored-by: Christian Clauss <cclauss@me.com>